[PATCH 6.1 329/473] usb: gadget: u_audio: Fix race condition use of controls after free during gadget unbind.

Greg Kroah-Hartman
2024-06-06T14:17:25Z

From: Chris Wulff <Chris.Wulff@biamp.com>

[ Upstream commit 1b739388aa3f8dfb63a9fca777e6dfa6912d0464 ]

Hang on to the control IDs instead of pointers since those are correctly
handled with locks.

Fixes: 8fe9a03f4331 ("usb: gadget: u_audio: Rate ctl notifies about current srate (0=stopped)")
Fixes: c565ad07ef35 ("usb: gadget: u_audio: Support multiple sampling rates")
Fixes: 02de698ca812 ("usb: gadget: u_audio: add bi-directional volume and mute support")
Signed-off-by: Chris Wulff <chris.wulff@biamp.com>
Link: https://lore.kernel.org/stable/CO1PR17MB5419C2BF44D400E4E620C1ADE1172%40CO1PR17MB5419.namprd17.prod.outlook.com
Link: https://lore.kernel.org/r/CO1PR17MB5419C2BF44D400E4E620C1ADE1172@CO1PR17MB5419.namprd17.prod.outlook.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/usb/gadget/function/u_audio.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c
index 4a42574b4a7fe..c8e8154c59f50 100644
--- a/drivers/usb/gadget/function/u_audio.c
+++ b/drivers/usb/gadget/function/u_audio.c
@@ -57,13 +57,13 @@ struct uac_rtd_params {

/* Volume/Mute controls and their state */
int fu_id; /* Feature Unit ID */
- struct snd_kcontrol *snd_kctl_volume;
- struct snd_kcontrol *snd_kctl_mute;
+ struct snd_ctl_elem_id snd_kctl_volume_id;
+ struct snd_ctl_elem_id snd_kctl_mute_id;
s16 volume_min, volume_max, volume_res;
s16 volume;
int mute;

- struct snd_kcontrol *snd_kctl_rate; /* read-only current rate */
+ struct snd_ctl_elem_id snd_kctl_rate_id; /* read-only current rate */
int srate; /* selected samplerate */
int active; /* playback/capture running */

@@ -494,14 +494,13 @@ static inline void free_ep_fback(struct uac_rtd_params *prm, struct usb_ep *ep)
static void set_active(struct uac_rtd_params *prm, bool active)
{
// notifying through the Rate ctrl
- struct snd_kcontrol *kctl = prm->snd_kctl_rate;
unsigned long flags;

spin_lock_irqsave(&prm->lock, flags);
if (prm->active != active) {
prm->active = active;
snd_ctl_notify(prm->uac->card, SNDRV_CTL_EVENT_MASK_VALUE,
- &kctl->id);
+ &prm->snd_kctl_rate_id);
}
spin_unlock_irqrestore(&prm->lock, flags);
}
@@ -807,7 +806,7 @@ int u_audio_set_volume(struct g_audio *audio_dev, int playback, s16 val)

if (change)
snd_ctl_notify(uac->card, SNDRV_CTL_EVENT_MASK_VALUE,
- &prm->snd_kctl_volume->id);
+ &prm->snd_kctl_volume_id);

return 0;
}
@@ -856,7 +855,7 @@ int u_audio_set_mute(struct g_audio *audio_dev, int playback, int val)

if (change)
snd_ctl_notify(uac->card, SNDRV_CTL_EVENT_MASK_VALUE,
- &prm->snd_kctl_mute->id);
+ &prm->snd_kctl_mute_id);

return 0;
}
@@ -1331,7 +1330,7 @@ int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,
err = snd_ctl_add(card, kctl);
if (err < 0)
goto snd_fail;
- prm->snd_kctl_mute = kctl;
+ prm->snd_kctl_mute_id = kctl->id;
prm->mute = 0;
}

@@ -1359,7 +1358,7 @@ int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,
err = snd_ctl_add(card, kctl);
if (err < 0)
goto snd_fail;
- prm->snd_kctl_volume = kctl;
+ prm->snd_kctl_volume_id = kctl->id;
prm->volume = fu->volume_max;
prm->volume_max = fu->volume_max;
prm->volume_min = fu->volume_min;
@@ -1383,7 +1382,7 @@ int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,
err = snd_ctl_add(card, kctl);
if (err < 0)
goto snd_fail;
- prm->snd_kctl_rate = kctl;
+ prm->snd_kctl_rate_id = kctl->id;
}

strscpy(card->driver, card_name, sizeof(card->driver));
--
2.43.0